1. Field of the Invention
The present invention relates to a method for measuring the mass flow rate of a multiple component, multi- phase fluid. More particularly, the present invention relates to a method for measuring the mass flow rate of a two phase fluid
2. Present State of the Art
In many applications, including geothermal applications, fluids are transported from one place to another. Often, the fluid is a multi-phase fluid meaning that it exists in one or more states. With regard to geothermal applications, the fluid is typically water and is in both a liquid and gaseous state. Because the fluid is being transported while in a multi-phase form, it is desirous to measure fluid flow related rates. The measurement of the mass flow rate is particularly useful.
Measuring the mass flow rate, however, has proven problematic. Early attempts to measure mass flow rate involved the use of intrusive or invasive devices, which involve placing some sort of sensor within the pipe that is transporting the multi-phase fluid. Intrusive mass flow measurement devices have not proven satisfactory. In many cases, including geothermal and petroleum applications, the fluid contains a wide variety of minerals and other compounds that are deposited on the measuring device, rendering the measuring device inaccurate or inoperable.
Another method of measuring mass flow rate involves the use of pressure ports. This method is less invasive than the method described above, but is subject to the same considerations. The chemical composition of the fluid may ultimately corrode or plug the pressure port, resulting in an inability to continuously provide mass flow rates.
Some external methods exist for measuring flow rates, but these methods require multiple sensors, compilations of data representing known fluid flows and complex mathematical manipulations. Preferably, a flow meter can determine the composition of flowing fluids without impeding the flow or reacting with the fluids. Clearly, invasive measurement devices do not satisfy this requirement. An external device and method capable of measuring the mass flow rate of a fluid without interfering with the fluid flow or reacting with the fluid is desirable.
The present invention has been developed in response to the present state of the art, and in particular, in response to these and other problems and needs that have not been fully or completely solved by currently available methods and apparatus for measuring fluid mass flow rates. Thus, it is an overall object of the present invention to provide a method and apparatus for reliably and non invasively measuring the mass flow rates of multi-phase fluids.
It is another object of one embodiment of the present invention to measure the mass flow rate of a multi-phase fluid without interfering with the fluid flow.
It is a further object of one embodiment of the present invention to measure the mass flow rate of a multi-component, multi-phase fluid.
In summary, the foregoing and other objects are achieved by providing a method and apparatus for measuring the mass flow rate of a multi-phase fluid. One embodiment of the present invention uses an accelerometer attached to a pipe which is transporting a multi-phase fluid. The multi-phase fluid flow is turbulent and produces vibrations in the pipe, which are measured by the accelerometer. In addition to the primary signal of the accelerometer, various noise components are superimposed on the primary signal. By analyzing the noise component, as defined by the standard deviation of the accelerometer signal, the mass flow rate of the fluid can be determined.
The analysis of the data produced by the accelerometer shows a definite relationship between the mass flow rate of the fluid and the noise component of the signal produced by an externally mounted accelerometer. In addition to measuring the mass flow rate of a multi-phase fluid, the present invention is non invasive.
Additional objects and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.